Inside the Crescent City Municipal Water Works building sits a vat of yellowish water.
It has a concentrate of 23 percent fluorosilicic acid, a chemical compound of fluoride.
This is diluted as it’s dripped into the city’s water supply flowing underground from the Smith River and is lessened even further by the time it comes out of the tap.
There are 4,200 “connections” to the city’s water system, including Pelican Bay State Prison and unincorporated suburbs near the city, said Utilities Director Eric Wier, but it’s estimated that about 14,000 people drink the water.
Only about one-third of those connections are inside city limits, he said.
Cities of at least 10,000 connections are required by the state to fluoridate drinking water. Since this is not the case for Crescent City, if Measure A passes Nov. 2, the pumps adding fluoride to the water will be turned off, he said.
In this structure built in 1958, chlorine is also added to the water as a disinfectant.
Fluorosilicic acid is the easiest to use and most common form of fluoride added to water, Wier said.
The amount of fluoride put in the drinking water is 1 part per million (ppm) or, in simpler terms, 1 milligram per liter (mg/L).
This is the optimal dose of fluoride in drinking water as defined by the state Department of Public Health’s Drinking Water Program.
The city is required to stay within a range of 0.9 to 1.5 mg/L, Wier said, explaining how that’s based on average daily temperature. In 2009, the average dosage rate 1.05 mg/L, he said.
An electronic monitor on the wall of the building shows how much fluoride and chlorine is being put in the water. On this day, it’s 1.18 ppm of fluoride — this will be diluted further to 1 ppm.
At the elevated water tanks where water is collected, samples are taken and tested daily to make sure fluoride stays at the optimal level, Wier said.
The monitor will alert city staff if too much or too little fluoride or chlorine is being put in the water, he said.
“Typically, it’s a little lower,” Wier said about when there’s an alert. “It’s very uncommon for it to go over.”
The city sends monthly reports on fluoridation to the state and once a year officials inspect the system, Wier said.
The city uses 4,800 to 5,000 gallons of fluoride in a year. It comes in 5,000-gallon drum from Basic Chemical Solutions based in Redwood City.
The local water system uses 800 million gallons of water in a year, Wier said, an average of 2 million gallons a day.
Fluorosilicic acid is one of three type of fluoride certified by the National Sanitation Foundation to be added to drinking water for the purpose of preventing and reducing tooth decay, according to the NSF.
It’s the byproduct of the manufacture of phosphate fertilizers, of which phosphate rock (containing fluorides and silica or silicates) is treated with sulfuric acid, according to a report by the National Institute of Environmental Health Sciences’s National Toxicology Program.
A report by the Center for Disease Control states: “since the chemicals used for water fluoridation are co-products of the man ufacture of phosphate fertilizers, and the raw material used is a natural resource (rocks excavated for their mineral content), water fluoridation could accurately be described as environmentally friendly, as it maxi mizes the use made of these natural resources, and reduces waste.”
Across the U.S., 80 million people drink water fluoridated with fluorosilicic acid, according to the CDC.
The practice of adding fluoride to municipal water systems began in the 1940s after researchers discovered residents had few cavities in communities with naturally fluoridated water.
In communities where the amount of naturally occurring fluoride was low, cavities were more prevalent and in those with a high concentrate of fluoride, residents had fewer cavities, but fluorosis (discoloration of the teeth) was common.
This is how the standard of fluoridating water at 1 part per million was established, according to the CDC.
Grand Rapids, Mich., was the first city to fluoridate its water in 1945. Now, about two-thirds of Americans drink fluoridated water, the?CDC?states.
Crescent City started fluoridating its water in 1968.
Fluoridation has long been a contentious issue here and went to a vote of city residents at least twice before, in 1960 and 1970.
Opponents have cited possible harmful effects and decried the notion of being forced to ingest fluoride.
The City Council put the fluoridation measure on the ballot in 1960, two years after first considering fluoridation and then backing off after some residents came out in force against it, according to Del Norte Triplicate archives.
City residents voted against fluoridation, 370-183, according to City Council meeting minutes. By 1970, sentiments about fluoridation had almost flipped.
The City Council appointed a committee to study fluoridation. The committee was in favor of it, and the practice began in 1968.
An opposition group gathered enough signatures to put the question of whether to continue fluoridation on the ballot.
In 1970, the vote was 441-178 in favor of continuing fluoridation.
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Utilities Director Eric Wier outside the fluoride tanks for the city water supply. (The Daily Triplicate/Bryant Anderson)
A fluoride tank for the city water supply. (The Daily Triplicate/Bryant Anderson)
Water technician Lennis Storey and a vat of diluted fluoride. (The Daily Triplicate/Bryant Anderson)
This map shows the general area served by Crescent City’s water district, including unincorporated suburbs. Not shown is the state prison, which also gets the water. (Submitted)